Dock seals are commonly used in association with loading docks to provide a seal between the end of a truck body parked in front of the loading dock and the dock. The use of a dock seal is particularly important when a loading operation is carried out at a cold storage warehouse to prevent warmer ambient air from entering the warehouse. Conversely, in cold weather climates it is desirable to provide a seal between the truck body and the dock to prevent the colder ambient air from entering the warehouse.
The conventional dock seal includes a pair of resilient side pads, commonly made of foam plastic material, which are mounted to the jambs along side the doorway on the loading dock. In addition, a header is mounted along the upper edge of the doorway and connects the upper ends of the two side pads. In order to accommodate truck bodies of varying height, the lower edge of the header extends a substantial distance beneath the upper end of the doorway. As the truck backs toward the loading dock, the end of the truck body will engage the header, pressing the header rearwardly to provide a seal between the header and the top surface of the truck body.
One common form of dock seal header is a flexible curtain or sheet formed of reinforced plastic or rubber coated fabric material. Headers of this type have very little insulating value, and as the truck body engages the flexible sheet and the header rides along the truck body, there is considerable abrasion of the header.
Inflatable dock seal headers have also been proposed, as disclosed in U.S. Pat. No. 4,821,468. However, headers of this type normally require a built-in blower for inflation. As a further problem, inflatable headers are frequently ruptured, thereby destroying the compressible nature of the header.
It has also been proposed to utilize foam plastic slabs as the header. However, a foam plastic slab is also subjected to abrasion as the truck body engages the header and the header rides against the truck body. Moreover, a thick foam slab lacks flexibility, so that the slab tends to pivot inwardly when engaged by the truck body, with the result that there is limited surface contact between the slab and the upper surface of the truck body.